I have the Raceland long-tube headers (S52). Bought them direct from Raceland though. They seem like decent quality. They are copies of the Supersprint ones. I had them ceramic coated. No idea about longevity yet. Also, mine went on at the same time as my S52 sc swap, so I can't comment on power before and after.
'07 335i/6 - Addicted to boost
'95 525 - money pit/daily driver
'90 525 S52, ERT Powerdyne Stage 2 Supercharger - parts car